The present invention relates to a hydrophobic substrate which is able to release a chemical substance and to a process for producing such a substrate.
Substrates are known which have the property of being able to release a chemical substance at a controlled speed for an extended period and such substrates are of great interest in numerous fields, particularly in the medical field.
Thus, such substrates can be used for the introduction into the human body of an active substance such as a medicament and a particular use thereof is in intrauterine devices which are able to release into the uterus during an extended period a substantially constant dose of an active substance such as a contraceptive agent.
The presently known processes for preparing substances of this type involve the formation in a first stage of hydrophilic or hydrophobic inclusions in a hydrophobic substrate, whilst the second stage consists of the absorption of a chemical substance in the hydrophilic or hydrophobic inclusions of the substrate.
In the substrates obtained by such processes the quantity of chemical substance stored in the substrate is limited by the number of hydrophilic or hydrophobic inclusions in the substrate and by the absorption capacity of the polymer constituting these inclusions. In addition, for certain applications such substrates have the disadvantage of containing an inadequate quantity of chemical substance.